1. Field of the Invention
This invention relates to highway sealants which are self leveling when applied and which bond to dolomite containing concrete when exposed to water immersion.
2. Background Information
Concrete highways are subjected to expansion and contraction forces which require that joints be placed in the construction to allow for expansion and contraction. The joint must be sealed or filled so that water can not fill the joint and then break the concrete when it freezes and expands. The joint must be filled so that it does not become filled with rocks, which would also cause the concrete to break when the joint narrows due to expansion of the concrete from weather changes.
Among the means used to fill the joints to keep out rocks have been molded elastomeric forms and poured or injected thermoplastic and/or elastomeric filling materials. When the roadway expands or contracts, these materials or devices allow the joint to become narrower or wider without subjecting the concrete to high physical forces. The simplest joint filler has been the use of hot melt asphalt. This functions at first, but fails due to hardening from aging or lowering of temperatures. More elaborate solutions have been molded elastomeric devices and the use of elastomers, such as polyurethanes and silicones, as joint filling materials.
U.S. Pat. No. 3,766,127, issued Oct. 16, 1973, teaches a low modulus room temperature vulcanizable silicone elastomer. The composition is based upon an acetamido containing chain extender and crosslinker in combination with a hydroxyl endblocked polydiorganosiloxane. When fillers are used in the composition it is useful as a sealant.
U.S. Pat. No. 3,817,909, issued June 18, 1974, teaches a low modulus room temperature vulcanizable silicone elastomer is obtained by mixing a hydroxyl endblocked polydiorganosiloxane, non-acidic, non-reinforcing filler, acetamido containing chain extender and crosslinker which is an aminoxysilicon compound having 3 to 10 aminoxy groups per molecule. The sealant is useful in building construction.
U.S. Pat. No. 3,996,184, issued Dec. 7, 1976, teaches a one package, low modulus, room temperaure vulcanizable silicone elastomer composition having improved slump characteristics at low temperatures. This composition is obtained by mixing a hydroxyl endblocked polydimethylsiloxane, non-acidic, non-reinforcing filler, methylvinyldi-(N-acetamido)silane, an aminoxysilicon compound having 3 to 10 aminoxy groups per molecule, and a diluent selected from N,N-dimethyl-formamide, acetonitrile, or N-n-butylacetamide. The elastomer is useful in building construction.
The sealant of this invention was developed to provide good bonding to dolomite containing concrete even when exposed to water immersion.